1. Field of the Invention
The invention relates to a developing device including a developing roller configured to develop an electrostatic latent image on a photosensitive drum to form a toner image on the photosensitive drum, and an image forming apparatus including the developing device.
2. Description of Related Art
In an electrophotographic printer, the method for forming an image includes the steps of charging, exposing light, developing, transferring, fixing, and cleaning.
In the developing process among those processes, a contact-type developing device using a single component non-magnetic toner is often used in view of downsizing and cost reduction. In the contact-type developing device, a developing roller is in contact with a photosensitive drum and voltage is applied to the developing roller, so that the toner is supplied from the developing roller to the photosensitive drum thereby developing the electrostatic latent image on the photosensitive drum.
Such a conventional developing device includes a development blade being in press-contact with the developing roller and thus forming a thin layer of the toner on the developing roller, a feed roller made of a foam member configured to feed the toner to the developing roller, an agitating member provided above a nip (a contact) between the developing roller and feed roller, and a toner supplier provided in the area above the feed roller and configured to supply the toner by intermittently contacting with the feed roller. The agitating member rotates in the same direction as the rotations of the developing roller and the feed roller while moving in a circular path and the toner supplier rotates in the opposite direction while moving in a circular path at a position opposed to the upper face of the feed roller. This configuration prevents clumped toner, in the vicinity of the feed roller, which is caused by contact and friction between the developing roller and feed roller or by the weight of the toner and which may causes less flowability of the toner, so as to prevent occurrence of fading in a printed image on a sheet (for example, see Japanese Patent Application Laid-Open No. 2005-172842, particularly see paragraphs 9035-0046 and FIG. 1).